The mammalian hematopoietic system comprises a number of protein factors that modulate cellular growth and differentiation. Included in the class of protein factors that regulate growth/differentiation are cytokines and chemokines. Some of these hematopoietic protein factors have been characterized and have provided the basis for clinically important pharmaceutical agents. Examples of hematopoietic protein factors that have been developed as pharmaceutical agents are erythropoietin (EPO) and granulocyte-colony stimulating factor (G-CSF). Other hematopoietic protein factors have found important uses in the neuronal system, such as epidermal growth factor (EGF) and fibroblast growth factor (FGF). These protein factors are used to support growth of cultured neuronal stem cells and progenitor cells. Still a host of other hematopoietic protein factors have been characterized which enable basic research efforts and support new technologies in various fields of endeavor.
Still to date, many mammalian hematopoietic protein factors remain uncharacterized. Thus, there is an important need to characterize mammalian hematopoietic protein factors that remain uncharacterized.